When you require the doctrine/doctrine-bundle package but not the doctrine/orm one you get the following exception:
[LogicException]
To configure the ORM layer, you must first install the doctrine/orm package.
This is because the https://github.com/symfony/recipes/blob/master/doctrine/doctrine-bundle/1.6/config/packages/doctrine.yaml#L4-L14 file is configuring the ORM which may be not installed.
I know this is not so easy as those configuration can't be moved in the doctrine/orm package as installing this one without the bundle would also break the application.